1. Field of the Invention
This invention relates to improvements in an airbag restraint unit of an airbag restraint system, and more particularly to such an airbag restraint unit of the type wherein an airbag is disposed above a gas generator, which is located inside a storage container having an gas ejection opening, so that gas from the gas generator is supplied through the gas ejection opening into the airbag.
2. Description of the Prior Art
Hitherto a variety of airbag restraint units have been known as devices for protecting passengers in a vehicle or the like. Such airbag restraint units are disclosed, for example, Japanese Utility Model Provisional Publication No. 2-38360, Japanese Patent Publication No. 56-43890 and Japanese Utility Model Provisional Publication No. 61-185642. The airbag restraint unit is disposed in a passenger compartment of the vehicle, or the like, and forms part of an airbag restraint system for protecting the vehicle passenger from coming into direct contact with a steering wheel or a windshield.
Additionally, Japanese Utility Model Publication No. 50-131742, Japanese Patent Provisional Publication No. 4-143142, and Japanese Patent Provisional Publication No. 5-262195 disclose an airbag cover which covers and stores thereinside an airbag in a folded state, and forms part of the airbag restraint unit.
Further, an airbag restraint unit 1 as shown in FIGS. 4, 5A and 5B has been known and arranged to be disposed inside an instrument panel 2 of a vehicle in a manner that the upper portion of the unit 1 is located near the inner surface of the instrument panel 1. This airbag restraint unit 1 is fixed to a support arm 4 mounted on a steering member 3. The airbag restraint unit 1 includes a cylindrical gas generator 5 which is stored in a storage container 6, which is secured to the support arm 4. The storage container 6 includes an base lower section 6a and a base upper section 6b. The base lower section 6a is opened at its upper section and has a generally U-shaped cross-section. The base upper section 6b is installed to the upper end portion of the opened upper section and formed with gas ejection openings 6c through which high pressure gas from the gas generator 5 flows upwardly when the gas generator 5 is operated. The gas generator 5 has a bolt section 5a protruding from an end face thereof. The bolt section 5a fits in an opening formed at an end wall of the base lower section 6a, and is fixed in position upon engagement with a nut so that the gas generator 5 is fixedly secured to the base lower section 6a.
An airbag 7 is fixed to the upper end face of the base upper section 6b in such a manner that a gas supply opening 7a of the airbag is communicated with the gas ejection openings 6c of the base upper section 6b. Additionally, an airbag cover 8 is fixed to the storage container 6 so as to cover the airbag 7 in the folded state.
At a vehicle collision or the like, high pressure gas from the gas generator 5 flows through the gas ejection openings 6c of the base upper section 6b and the gas supply opening 7a of the airbag 7 and is supplied into the airbag 7. As a result, the airbag 7 inflates and then opens or breaks the airbag cover 8 so as to project toward the vehicle passenger thereby protecting the vehicle passenger from coming into direct contact with inside parts (such as a steering wheel and a windshield) within the passenger compartment.
However, drawbacks have been encountered in the above-discussed conventional airbag restraint unit as shown in FIGS. 4, 5A and 5B. That is, the storage container 6 of the airbag restraint unit 1 includes the base lower and upper sections 6a, 6b, and therefore is relatively heavy in weight and high in production cost.
In view of this, it has been proposed to omit the base upper section 6b so that the airbag 7 is secured at its part defining the gas supply opening 7a to the upper end portion of the opened upper section of the base lower 6a as shown in FIGS. 6A and 6B. However, in this case, there is the possibility that the folded and stored state of the airbag 7 is unavoidably released or broken when or after the airbag 7 is stored in the base lower section 6a, since the airbag 7 is pressed into a position above the gas generator 5 under its folded and stored state.
However, even such an airbag restraint unit of FIGS. 6A and 6B has the following difficulties: If the folded and stored state of the airbag 7 is released, there is a fear that the airbag 7 cannot smoothly inflate. Additionally, an assembly operation must be made maintaining the folded and stored state of the airbag 7 during assembly of the airbag restraint unit 1, and therefore there is a fear of an operational efficiency being lowered. Further in both cases that the base upper section 6b is used and not used, high pressure and temperature gas comes into direct contact with sewing threads of the airbag 7 to provide the possibility of the sewing threads of the airbag 7 being broken. As a result, it may affect a restraining performance of the airbag 7 for a vehicle passenger.